Japan lost a quarter of its electric capacity when it shuttered its nuclear reactors in the wake of the Fukushima disaster. Predicted blackouts have not materialized, though, thanks to a national conservation effort that reduced demand by as much as 15 percent.

But the Japanese people have "suffered" with thermostat settings of 83 in summer, according to a Tokyo Gas Company executive studying energy efficiency at Stanford University. They may run short of power this winter, he added, and conservation efforts cannot be expected to endure.

"Thermostats set to 83 degrees? This isn't energy efficiency. It's just pushing people to suffer," said Toshiya Okamura of Tokyo Gas, a visiting scholar at Stanford University's Precourt Energy Efficiency Center.

"But the government is saying that these voluntary savings will persist. I don't agree," Okamura said in an interview released by Stanford's News Dept.

Toshiya Okamura (Stanford)

Summer energy savings dropped from 15 percent in 2011 to 10 percent in 2012, he noted. And Okamura predicts more power may needed this winter in Japan, where many heaters are electric.

"People did everything they could," said Okamura. "To minimize air conditioning, they raised thermostats in homes, offices and stores to 83 degrees Fahrenheit, as the government asked. They set every appliance and electronic device to the most energy-efficient settings. They kept the lights off as much as possible. Escalators were shut off."

The Japanese also benefitted from heavy rains that boosted hydropower and from unusually reliable fossil-fuel generators, he said.

Although America may seem an odd place to study energy conservation—per capita energy use has increased 50 percent here in 40 years, conservation is even less natural to Japan, according to Okamura, and California, in particular, may provide a useful model. Defying the trend in the rest of the United States, Californians have kept their energy consumption per capital at about the same level since 1974, according to the Washington Post.

"The United States and Europe are still learning how to do this, especially regarding behavior change, but you are 10 to 20 years ahead of us on this," Okamura said.

In the U.S. Okamura hopes to learn how to reduce waste so that his nation can continue to produce more energy and maximize its benefits:

"One thing I've learned here is that energy efficiency is about reducing waste – that is, producing more and enjoying the same amenities with lower energy inputs."